Help: What my pistons look like.

[jastermerrel]

Hey guys. I took the head off today and this is what I've found. History: Car was sitting 3 months. I goofed and cross threaded a spark plug and took the head today to go get it helicoiled. Looks like it was running very rich? That is my only explanation for the black flaky stuff that is in ever cylinder and on my intake valves. Exhaust valves are white. Also I had a lot of gunk (oily sludge) in the intake manifold and intake ports on the head. No gunk past the throttle body butterfly valve (away from the motor). What do I need to do? Car is essentially stock. Except that I had the t25 rebuilt to a t28. Block and head were stock rebuilt 3 years ago, with about 30k on them. What needs to be done to keep this from happening after I get it all put back together. No CEL's where being thrown by the way.

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Thanks!

 

[diambo4life]

Wow! WTF I'm speechless. What were the compression numbers? Did the car eat/burn oil?

 

[jastermerrel]

The car did go through some oil...not a whole lot maybe a quart every 3-4 weeks. I attributed that to a leak in my front case. The whole timing side of the motor is oily which is another reason for the car being down. I'm beginning to wonder if my valve stem seals are shot. Which I guess would explain what I'm seeing in the cylinders. I didn't check compression before I pulled the head. The car ran fine before I started pulling it apart. The cylinder walls look fine.

 

[romeen]

WTF Definitely has my curiosity. Are those flakes just loosely sitting on top of the pistons? How hard are they, can you easily break them apart with your fingers? Do you know if the pistons were coated?

 

[1992awdlaser]

Valve seals will also show signs of oil in some runners of the head 99% of the time. It will be just like you described, sludge. So, that is a good guess at what it is.

 

[jastermerrel]

Yea, it is just loose flaky carbon deposits. Not hard at all. Guess its time for a head rebuild. Just had it rebuilt 3 years ago just normal driving. I don't race this car at all. Guess the guy that rebuilt it didn't do a very good job.

 

[VETTE_50_TH]

Did you have animals living in the cylinders bringing home bark and then you came to start the car and it melt or something? That looks so sick nasty.

James

 

[romeen]

Damn. It looks like there is enough volume of crap there to have significantly raised your compression. And talk about hot spots which could cause detonation.

I'm surprised that the flakes didn't break down to smaller particles and make their way out throught the exhaust. You might want to check the condition of the blades on your turbine wheel.

 

[DougR]

Ok guys what your looking at is Leaky Valve seals, Massive Blow by and a Extreme Lean condition.
look at pic 3 lower left and right valve. right at the edge of the valve and combustion chamber its still wet with oil...
I would imagine Every intake valve probly looks almost identical...
Also I would bet that his fuel filter is almost completly clogged. Add in the turbo upgrade from t-25 to
t-28 and there is the lean condition causing White exhaust valves and Plug Ground straps.

What has happened in my mind. is this..... The car was driven Along time with leaking valve seals and blow by, starting the extreme carbon buildup. After the Turbo rebuild and introducing the Lean condition, The carbon started breaking up... Along with sitting for months the carbon started to dry out and flakeing off, Which is why the combustion dome and valves are somewhat clear of carbon buildup..
Also when he pulled the head off it broke the carbon seal from the head to block, which pulled off alot of the carbon in the combustion dome causing ALOT of the loose carbon on top of the pistons.

I would tear that entire block and head apart and clean it. have it and the head checked for warping.
Did this car ever! overheat?

Regardless bro. Its rebuild time... If you dont get ALL of that carbon flake out. It will score the cylinder walls (causing even more blow by) and valves, Seats. guides. etc.... Trashing the entire motor.

Good luck dude....


BTW Guys. This is what Sea foam and Water injection CLEANS OUT!

 

[delta448]

^Exactly.
I was going to give a slightly more abbreviated version of DougR's reply, but he beat me to it. The engine either first ran rich... then lean -or more likely, ran hot while simultaneously chugging oil like Belushi in Animal House. OP, you need to locate and eliminate wherever that oil sludge is coming from.

The obvious signs of a high temperature condition are the white exhaust valves and glazed spark plug tip.

edit: reworded in italics

 

[1992awdlaser]

Lots of cars have white exhaust valves even if the car isn't running lean. Same with too hot of a plug.

 

[romeen]

Also when he pulled the head off it broke the carbon seal from the head to block, which pulled off alot of the carbon in the combustion dome causing ALOT of the loose carbon on top of the pistons.

This makes sense.

 

[delta448]

Lots of cars have white exhaust valves even if the car isn't running lean. Same with too hot of a plug.

Yes, but that is most likely because of the timing adjustments or the tune as a whole on those cars. The temperature is what causes the white appearance. A well tuned engine will turn the exhaust valves and the turbine blades white. A lean engine will turn them white without making any power.

 

[1992awdlaser]

Yes, but that is most likely because of the timing adjustments or the tune as a whole on those cars. The temperature is what causes the white appearance. A well tuned engine will turn the exhaust valves and the turbine blades white. A lean engine will turn them white without making any power.

I don't mean just on modded cars. My car for instance had white exhaust valves when I pulled the head even though it was not running lean. This is when the car was stock. It's because exhaust valves on some cars have content of a certain element in them. I forget what it is though. I'm not saying that this car is or isn't running lean. I'm just saying because the valves are white does not necessarily mean it was running lean.

 

[jastermerrel]

Hey everyone thanks for the replies.
Everything I had read on this site and others led my to believe that I would be fine with the t28 keeping everything else stock (as in it would not cause lean issues) 3 years ago when I had it rebuilt. Still running off stock boost. I think i'm going to attempt to rebuild the head myself, I have the confidence...just not the know how. It would be a good experience anyway.

 

[delta448]

It's because exhaust valves on some cars have content of a certain element in them. I forget what it is though. I'm not saying that this car is or isn't running lean. I'm just saying because the valves are white does not necessarily mean it was running lean.

First, I think we're in agreement. It doesn't necessarily mean it was lean, just that it was hot. I edited my first post here before your reply, but I guess you didn't see that.

I think the element you're thinking of is sodium.

 

[1992awdlaser]

First, I think we're in agreement. It doesn't necessarily mean it was lean, just that it was hot. I edited my first post here before your reply, but I guess you didn't see that.

I think the element you're thinking of is sodium.

Yeah, we are in agreement. I just didn't want people to think the only reason for a white exhaust valve is due to running lean. Nope, I didn't notice you edited your post.

 

[phunny]

Holy blow-by batman.......You sure there's no scaring or anything? How's the turbo look? You could tear it down and freshen it up or.........Get a 55gallon drum of SEAFOAM

 

[elementalwindx]

Ok guys what your looking at is Leaky Valve seals, Massive Blow by and a Extreme Lean condition.
look at pic 3 lower left and right valve. right at the edge of the valve and combustion chamber its still wet with oil...
I would imagine Every intake valve probly looks almost identical...
Also I would bet that his fuel filter is almost completly clogged. Add in the turbo upgrade from t-25 to
t-28 and there is the lean condition causing White exhaust valves and Plug Ground straps.

What has happened in my mind. is this..... The car was driven Along time with leaking valve seals and blow by, starting the extreme carbon buildup. After the Turbo rebuild and introducing the Lean condition, The carbon started breaking up... Along with sitting for months the carbon started to dry out and flakeing off, Which is why the combustion dome and valves are somewhat clear of carbon buildup..
Also when he pulled the head off it broke the carbon seal from the head to block, which pulled off alot of the carbon in the combustion dome causing ALOT of the loose carbon on top of the pistons.

I would tear that entire block and head apart and clean it. have it and the head checked for warping.
Did this car ever! overheat?

Regardless bro. Its rebuild time... If you dont get ALL of that carbon flake out. It will score the cylinder walls (causing even more blow by) and valves, Seats. guides. etc.... Trashing the entire motor.

Good luck dude....


BTW Guys. This is what Sea foam and Water injection CLEANS OUT!

I was thinking exactly what this guy was saying. My 95 gst had this the first time I removed the head. But not exactly as bad. Just clean the pistons, properly freshen up the head and your good to go for the most part.